422 GEOLOGY OF THE SECOND RISTRICT. 



CHAPTER XII. 



On Drift. — Grooves and Scorings of the Rocks of the Second District. — [Hypotheses. — 

 Depression or Submergence, and Gradual Rise. — Glacial Theory. — Remarks on the 

 necessity of a classification of facts, etc. 



In this chapter, I propose to condense into one view tlie fuels in relation to drift and liic 

 subjects related thereto, so far at least as they receive illustration in the geological structure 

 of the Second district. For a full and clear understanding of these phenomena, it is necessary 

 to bring together the facts relating to each, such as the distribution of boulders, the scoring 

 of rocks, the position of the tertiary, etc. I shall therefore recapitulate briefly these facts, 

 preparatory to summing up the inferences which may be deduced from them. 



1. Distribution of boulders. It has been stated that the boulders and drift of the north are 

 arranged in a belt between two and three hundred feet above the level of the great lakes, at 

 the bases or upon the lower terraces of the hills which lie between the Champlain and the St. 

 Lawrence waters. At least they are more abundant at this height than either below or above, 

 though they occur between two and three thousand feet higher. Boulders may be divided into 

 two classes : 1st, those which evidently belong to regions remote from tlieir present location ; 

 and 2dly, those which belong either to the rock immediately beneath the surface, or to one 

 but a short distance therefrom : the former class are rounded, and the latter angular. The 

 boulders on the cast side of Lake Champlain belong almost exclusively to the rock immediately 

 below the surface, for which I shall be able to give a reason. 



2. The scorings of rock, or scratches. Their direction conforms to that of the great valleys. 

 In the Champlain valley, it is nearly north and south ; and in the St. Lawrence valley, north- 

 east and southwest. It is necessary to class with these the deep grdovings noticed under 

 Jeflerson county (see p. 369). Perforations belong to another class of phenomena, being 

 produced always by waters moving in eddying currents, and carrying around stones, sand and 

 gravel. 



3. Tertiary of Champlain. This is deposited from quiet waters, and always 'overlies the 

 scored and grooved surfaces. It is marine, and contains many fossils and some boulders, but 

 the latter are extremely rare e.xcept in a few places. In many places the tertiary lies beneath 



